Matter which have no definite shape and volume
Gases
Matter: Anything or everything which occupies space, possesses mass, and offers resistance to any stress applied to it is called matter.
The explanation for the correct option:
Option(C) Gases: Gases have neither a fixed shape nor a fixed volume
The explanation for the incorrect option:
Option(A) Solid: Solids have a definite shape, distinct boundaries, and fixed volumes.
Option(B) Liquid: Liquid has a definite volume not a definite shape.
Gases have no definite shape and volume, hence option (C) is correct.